JP2007286559A - Heating device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating device which is a heating device using electromagnetic induction using a heating rotator and can improve efficiency of induction heating by preventing magnetic flux from being discharged and improving efficiency when the heating rotator exceeds a curie point, and an image forming apparatus. <P>SOLUTION: The heating device 1 having the heating rotator 10 having an electromagnetic induction heating member 11, a magnetic flux generating means 15 of applying magnetic flux to the electromagnetic induction heating member 11 to generate heat, and a pressing member 30 which abuts against the heating rotator 10 is provided with a magnetic flux capturing means 50 of capturing magnetic flux passed through the electromagnetic induction heating member 11 with magnetic flux generated by the magnetic flux generating means 15 by using the electromagnetic induction heating member 11 almost at the curie point. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention generally relates to a heating device that pressurizes and heats a material to be heated, and in particular, heats an unfixed toner image formed on a recording material using, for example, an electrophotographic process, an electrostatic recording process, a magnetic recording process, or the like. The present invention relates to a heating device for fixing. The present invention also relates to an image forming apparatus having such a heating device.

  Conventionally, for example, in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, a latent image corresponding to target image information is formed on an image carrier by an image forming process means. This latent image is made into a visible image (toner image) using toner made of heat-meltable resin or the like, and then this toner image is directly applied to the surface of a recording material such as transfer paper or intermediate transfer. The toner image is transferred through the body to form an unfixed toner image on the recording material surface.

  As a fixing device for fixing an unfixed toner image as a permanently fixed image on a recording material surface, a heating device of a heat roller type is generally used. In this heating apparatus, a toner image is heated and pressed and fixed by nipping and conveying a recording material as a heated material by a heating roller heated to a predetermined temperature and a pressure roller pressed against the heating roller.

  In recent years, there has been proposed a heating device that generates an eddy current in the fixing film itself or a conductive member close to the fixing film and generates heat by Joule heat at that time (see, for example, Patent Document 1).

Moreover, the proposal which hold | maintains the temperature of a heating rotary body using the Curie point of a heating rotary body is made | formed (for example, refer patent document 2).
Japanese Patent No. 3311111 Japanese Patent No. 2975435

  When the temperature of the heating rotator is held using the Curie point as described above, the heating rotator becomes paramagnetic when the Curie point is exceeded, so the magnetic flux generated from the magnetic flux generating means is released from the heating rotator. There was a problem that. When such a phenomenon occurs, the efficiency of induction heating decreases.

  Therefore, an object of the present invention is to prevent induction of magnetic flux and improve efficiency when the heating rotator exceeds the Curie point in a heating apparatus using electromagnetic induction using a heating rotator, and improve the efficiency of induction heating. It is an object to provide a heating device and an image forming apparatus that can improve the image quality.

The above object is achieved by the heating device and the image forming apparatus according to the present invention. In summary, according to one aspect of the present invention, a heating rotator having an electromagnetic induction exothermic member, magnetic flux generating means for generating heat by putting magnetic flux in the electromagnetic induction exothermic member, and abutting the heating rotator. In a heating device that includes a pressure member, and pressurizes and heats the material to be heated in a nip formed by contact between the heating rotator and the pressure member,
A heating apparatus characterized in that the electromagnetic induction heat generating member is used in the vicinity of a Curie point, and a magnetic flux capturing means is provided for capturing the magnetic flux that has passed through the electromagnetic induction heat generating member with the magnetic flux generated by the magnetic flux generation means. Provided.

According to a second aspect of the present invention, in an image forming apparatus comprising: an image forming unit that forms an unfixed toner image on a recording material; and a fixing device that thermally fixes the unfixed toner image on the recording material.
An image forming apparatus is provided in which the fixing device is the heating device.

  According to the present invention, when the heating rotator using the electromagnetic induction heat generating member is used beyond the Curie point, the magnetic flux transmitted from the heating rotator can be captured by the magnetic flux capturing means. Can prevent leakage.

  In addition, the heating rotator can be induction-heated again by the induced current generated in the magnetic flux capturing means by the magnetic flux that has passed through the heating rotator, and the induction heating efficiency can be improved.

  Hereinafter, a heating device and an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Example 1
FIG. 1 shows an embodiment of an image forming apparatus provided with a heating device according to the present invention. In this embodiment, the image forming apparatus is an electrophotographic tandem color image forming apparatus, but the image forming apparatus that can employ the heating apparatus of the present invention is not limited to this.

(1) Image Forming Apparatus With reference to FIG. 1, the overall configuration of the image forming apparatus of this embodiment will be described first.

  In this embodiment, the image forming apparatus 100 includes four image forming stations S (Sa) of yellow (Y), magenta (M), cyan (C), and black (Bk) in the image forming apparatus main body 100A. , Sb, Sc, Sd) are juxtaposed in series in the image feed direction. Each of the image forming stations S (Sa, Sb, Sc, Sd) is a drum-shaped electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 101 (101a, 101b) as an image carrier constituting the image forming means. , 101c, 101d). Around each photosensitive drum 101, further, a charging device 102 (102a, 102b, 102c, 102d) serving as a charging unit and an exposure device 103 (103a, 103b, 103c, 103d serving as an exposure unit) constituting an image forming unit. ) And developing devices 104 (104a, 104b, 104c, 104d) as developing means. Further, around each photosensitive drum 101, a cleaning device 105 (105a, 105b, 105c, 105d) as a cleaning unit and a transfer device 107 (107a, 107b, 107c, 107d) as a transfer unit are arranged. Yes.

  Further, the transfer belt 106 is disposed so as to pass between the photosensitive drum 101 (101a, 101b, 101c, 101d) and the transfer device 107 (107a, 107b, 107c, 107d) of each image forming station S. The transfer belt 106 is wound around and supported by support rollers 106a and 106b, and is movable in the direction of the arrow.

  An image forming operation of the image forming apparatus having the above configuration will be briefly described.

  First, in each image forming station S, the photosensitive drum 101 is uniformly charged by a charging device 102 serving as a charging roller. An optical image is irradiated on the charged photosensitive drum 101 from an exposure device 103 serving as a laser beam scanner unit disposed above the image forming apparatus main body 100A, and an electrostatic latent image corresponding to the image signal is applied to the photosensitive drum 101. Is formed.

  Each developing device 104 is filled with a predetermined amount of a developer in which a nonmagnetic toner of yellow, magenta, cyan, and black and a magnetic carrier are mixed at a predetermined mixing ratio. The developing roller 104A (104Aa, 104Ab, 104Ac, 104Ad) disposed in each developing device 104 sequentially develops the latent image on the photosensitive drum 1 with toner of each color to form a toner image.

  The recording material P stored in the recording material cassette 110 is fed onto the transfer belt 106 by a paper feed roller 111, a transport roller 112, and the like. The yellow, magenta, cyan, and black toner images on the respective photosensitive drums are transferred onto the recording material P conveyed to the respective image forming units by the transfer belt 106 by a transfer device 107 serving as a transfer roller.

  In this embodiment, the recording material P to which the toner image has been transferred is conveyed to a heating device 1 serving as a fixing device, and the temperature of the toner image on the recording material P is changed by a fixing nip portion formed in the heating device 1. Heat fixing by controlling. The recording material P is discharged from the apparatus as a recorded image after the toner image is fixed by the heating device 1.

  On the other hand, residual toner or the like remaining on the photosensitive drum 101 (101a, 101b, 101c, 101d) is cleaned by a photosensitive drum cleaning device 105 (105a, 105b, 105c, 105d) including a cleaning blade unit.

  Next, the heating device will be further described.

(2) Heating device 1
In this embodiment, the heating device 1 that functions as a fixing device is an electromagnetic induction heating type heating device. FIG. 2 is a schematic configuration diagram illustrating a transverse side surface of a main part of the heating device 1 of the present embodiment, and FIG. 3 is a front schematic diagram of the main part.

  Referring to FIG. 2, in this embodiment, the heating device 1 includes a heating rotator 10 and a pressure member 30 that contacts the heating rotator 10 and forms a fixing nip N between the heating rotator 10 and the heating rotator 10. Have

  The heating rotator 10 is an electromagnetic induction heat generating rotator, and is a cylindrical heating roller in this embodiment. As is understood with reference to FIG. 4, the heating roller 10 includes a heat generating layer 11 made of an electromagnetic induction heat generating metal or the like serving as a core metal, and an elastic layer laminated on the outer surface thereof. This is a composite structure of the layer 12 and the release layer 13 laminated on the outer surface thereof. For adhesion between the heat generating layer 11 and the elastic layer 12 and adhesion between the elastic layer 12 and the release layer 13, a primer layer (not shown) may be provided between the respective layers.

  In the heating roller 10, the heat generation layer 11 is on the inner surface side, and the release layer 13 is on the outer surface side in contact with the pressing member 30 or the recording material (heated material) P.

  The configuration of the heating roller 10 will be further described later.

  Further, according to the present embodiment, an electromagnetic induction heat generating member, that is, a magnetic flux generating means 15 for generating heat by putting magnetic flux into the cored bar 11 which is a heat generating layer is arranged inside the heating roller 10.

  In this embodiment, the magnetic flux generation means 15 includes magnetic cores 17a, 17b, 17c and an excitation coil 18, as shown in FIG. The magnetic core 17 a extends in a vertical direction, that is, in a radial direction from a substantially central portion in the cross section of the heating roller 10, and the magnetic cores 17 b and 17 c are magnetically positioned in a substantially central portion in the cross section of the heating roller 10. It extends in the radial direction from the core 17a to both sides in the horizontal direction.

  Further, the magnetic cores 17a, 17b, 17c and the exciting coil 18 have an upper surface formed in an arc shape along the inner surface of the heating roller 10, and are integrally held by an arc-shaped holder 16 disposed in the upper arc-shaped portion. Has been. Therefore, the magnetic coil 18 is disposed in a fixed state between the holder 16 and the magnetic cores 17a, 17b, and 17c.

  Further, a flat lower surface formed by the magnetic cores 17 b and 17 c on the side opposite to the upper arc-shaped portion of the exciting coil 18 is supported on the holding stay 22 via the insulating member 19. Thereby, the magnetic flux generation means 15 is installed in the heating roller 10 along the roller longitudinal axis direction. The holding stay 22 can be made of a metal material such as iron, aluminum, stainless steel, or nonmagnetic stainless steel. Further, it is sufficient if the magnetic flux generating means 15 can be held, and a heat resistant resin can be substituted.

  The magnetic cores 17a, 17b, and 17c are high magnetic permeability members, and are preferably made of a material used for a transformer core such as ferrite or permalloy, and more preferably ferrite having a low loss even at 100 kHz or higher. Further, an iron core in which silicon steel plates or the like are laminated can also be used.

  The exciting coil 18 is a conductive wire (electric wire) that constitutes a coil (wire ring), and uses a bundle (bundle) of a plurality of thin copper wires, each of which is coated with an insulation coating, and is wound several times. An exciting coil is formed. Further, an excitation circuit (not shown) is connected to the excitation coil 18 so that a high frequency of 20 kHz to 500 kHz can be generated by a switching power supply. The exciting coil 18 generates an alternating magnetic flux by an alternating current (high-frequency current) supplied from the exciting circuit.

  As described above, the holder 16 has a substantially semicircular arc shape in cross section, and holds the magnetic cores 17a, 17b, 17c and the exciting coil 18 inside. In addition, a heating roller 10 that is a cylindrical electromagnetic induction heat generating rotating body is rotatably disposed with a gap outside the holder 16.

  The magnetic flux generated by the magnetic flux generation means 15 is guided to the magnetic cores 17a, 17b, and 17c, and the heating roller 10 generates heat between the magnetic core 17a and the magnetic core 17b and between the magnetic core 17a and the magnetic core 17c. An eddy current is generated in the layer 11. This eddy current causes Joule heat (eddy current loss) to be generated in the heat generating layer 11 by the specific resistance of the heat generating layer 11.

  Next, the heating roller 10 will be further described with reference to FIGS. FIG. 4 is a schematic diagram of the layer structure of the heating roller 10 in this embodiment as described above.

  In the heating roller 10 of this embodiment, the above-described alternating magnetic flux acts on the heat generating layer 11, so that an eddy current is generated in the heat generating layer 11 and the heat generating layer 11 generates heat. This heat is transmitted to the elastic layer 12 and the release layer 13 so that the entire heating roller 10 is heated, and the recording material P passed through the fixing nip portion N is heated to fix the toner image t by heat.

  As the heat generating layer 11, a ferromagnetic metal such as nickel-iron alloy, nickel, iron, ferromagnetic stainless steel, nickel-cobalt alloy, and permalloy is used. The thickness of the heat generating layer 11 is preferably greater than the skin depth δ [m] represented by the following formula and 1.5 mm or less.

  If the thickness of the heat generating layer 11 is within this range, the heat generating layer 11 can efficiently absorb electromagnetic waves, and therefore heat can be generated efficiently.

Here, f is the frequency [Hz] of the excitation circuit, μ is the magnetic permeability of the heat generating layer 1, and κ is the conductivity of the heat generating layer 1.

  This skin depth δ indicates the depth of absorption of electromagnetic waves used for electromagnetic induction, and the intensity of the electromagnetic waves is 1 / e or less deeper than this. In other words, most of the energy is absorbed up to this depth (see the relationship between the heat generation layer depth and the electromagnetic wave intensity shown in FIG. 5).

  The thickness of the heat generating layer 11 is more preferably 0.1 to 0.8 mm. When the thickness of the heat generating layer 11 is thinner than the above range, it is difficult to maintain the shape as a roller. On the other hand, when the heat generating layer 11 is thicker than the above range, the heat capacity is increased and the temperature raising rate is decreased.

  Moreover, the heat generating layer 11 sets the Curie temperature within the normal use temperature. Since the ferromagnetic material becomes paramagnetic when it reaches the Curie point, the magnetic flux generated by the exciting coil 18 penetrates the heat generating layer 11. That is, since only the magnetic flux passes through the heat generating layer 11, the magnetic flux per unit area of the heat generating layer 11 decreases, and the amount of heat generation decreases drastically.

  For example, a predetermined fixing temperature can be maintained by providing the Curie point in the vicinity of the fixing temperature. That is, when the temperature of the heating roller 10 is lowered by passing paper and falls below the Curie point, the heat generating layer 11 is again induction-heated, and thereby the temperature is adjusted in the vicinity of the Curie point.

  The elastic layer 12 is preferably made of a material having good heat resistance and thermal conductivity, such as silicone rubber, fluorine rubber, and fluorosilicone rubber.

  The thickness of the elastic layer 12 is preferably 0.05 to 3 mm in order to guarantee the fixed image quality. When a color image is printed, a solid image is formed over a large area on the recording material P, particularly in a photographic image. In this case, if the heating surface (release layer 13) cannot follow the unevenness of the recording material P or the unevenness of the toner image t, uneven heating occurs, and uneven gloss occurs in the image where the heat transfer amount is large and small. That is, the glossiness is high in the portion where the heat transfer amount is large, and the glossiness is low in the portion where the heat transfer amount is small. When the thickness of the elastic layer 12 is smaller than the above range, the release layer 13 cannot follow the unevenness of the recording material P or the toner image t, and image gloss unevenness occurs. On the other hand, when the elastic layer 12 is too larger than the above range, the thermal resistance of the elastic layer 12 becomes too large and the thermal response becomes slow. The thickness of the elastic layer 12 is more preferably 0.1 to 2.5 mm.

  If the hardness of the elastic layer 12 is too high, the unevenness of the recording material P or the toner image t cannot be fully followed and unevenness in image gloss occurs. Therefore, the hardness of the elastic layer 12 is 60 ° or less (JIS-A: using a JIS KA type measuring device), more preferably 45 ° or less.

  The thermal conductivity λ of the elastic layer 12 is preferably 0.25 to 0.84 W / m · K. When the thermal conductivity λ is smaller than the above range, the thermal resistance is too large, and the temperature rise in the surface layer (release layer 13) of the fixing film 10 becomes slow. When the thermal conductivity λ is larger than the above range, the hardness of the elastic layer 12 becomes too high or compression set tends to occur.

  The release layer 3 is preferably made of a material having good release properties and heat resistance such as fluororesin, silicone resin, fluorosilicone rubber, fluororubber, silicone rubber, PFA, PTFE, and FEP.

  The thickness of the release layer 13 is preferably 1 to 100 μm. When the thickness of the release layer 13 is thinner than the above range, uneven coating of the coating film occurs, and there arises a problem that a part having poor release properties occurs or durability is insufficient. Further, when the thickness of the release layer 13 is thicker than the above range, the heat conduction is deteriorated. In particular, when a resin material is used for the release layer 13, the hardness of the release layer 13 becomes too high and the effect of the elastic layer 12 is lost.

  In this embodiment, the pressure roller as the pressure member 30 is made of a core metal 30a and heat resistance / elasticity such as silicone rubber, fluororubber, and fluororesin formed and coated concentrically around the core metal 30a. The release layer 30c is provided on the surface layer. The thickness and material of each layer can be selected similarly to the heating roller 10.

  In both the heating roller 10 and the pressure roller 30, the release layer 13 and the elastic layer 12 can be provided with conductivity by mixing, for example, carbon black such as ketjen black or metal powder such as aluminum.

In this embodiment, as shown in FIG. 3, the temperature detection elements 26 and 27 are installed outside the heating roller 10. Although the temperature detection elements 26 and 27 and the heating roller 10 are in a non-contact state, they can be placed in a contact state for the purpose of improving responsiveness and accuracy. It can also be arranged inside. The temperature detecting element 26 is disposed at the center in the longitudinal direction of the heating roller 10, and the temperature detecting element 27 is disposed inside the maximum sheet width L _Pmax .

  As shown in FIG. 3, the heating roller 10 is rotatably supported by the fixing frame 44 via a bearing 41. The pressure roller 30 is urged through a bearing 42 so that the pressure roller 30 is pressed against the heating roller 10 by a pressure spring 45 as pressure means. A gear 43 is attached to one end of the heating roller 10 so as to rotate integrally with the heating roller 10. The heating roller 10 is rotationally driven by the driving means M in the clockwise direction indicated by the arrow (see FIG. 2).

  As shown in FIG. 2, according to the heating device 1 of the present embodiment, the magnetic flux capturing means 50 is disposed outside the heating roller 10 and opposed to the magnetic flux generating means 15.

  The magnetic flux capturing means 50 includes a magnetic flux capturing coil 51 and a magnetic core 52. The magnetic flux capturing coil 51 is disposed opposite to the exciting coil 18 and is disposed along the outer peripheral surface of the heating roller 10 at a predetermined distance. As shown in FIG. 6, the magnetic flux capturing coil 51 is configured as a closed loop having no open end. The magnetic flux capturing coil 51 uses a bundle (bundled wire) of a plurality of thin copper wires, each of which is insulated and coated, as a conducting wire (electric wire) that constitutes a coil (wire ring) in the same manner as the exciting coil 18. be able to. A single wire or a sheet coil can also be used. The thickness and the number of turns of the line can be determined according to the frequency and the current flowing per unit area.

  A magnetic core 52 is disposed outside the magnetic flux capturing coil 51 along the outer periphery of the magnetic flux capturing coil 51. The magnetic flux capturing coil 51 and the magnetic core 52 are held by an insulating support member (not shown) and hold a distance from the heating roller 10.

  The magnetic flux penetrating from the portion exceeding the Curie point in the heat generating layer 11 of the heating roller 10 generates an induced current in the magnetic flux capturing coil 51. Since the magnetic flux capturing means 50 is disposed along the length of the heat generating layer 11, the generated induced current induction heats a portion of the heat generating layer 11 that does not exceed the Curie point. Therefore, the magnetic flux capturing means 50 captures the magnetic flux that has been released to the outside from the portion exceeding the Curie point and has not contributed to the heat generation when the heat generating layer 11 exceeds the Curie point, and can be used again for the heat generation of the heat generating layer 11. Therefore, power consumption can be reduced.

  Two specific examples will be described below.

(1) With respect to temperature drop at the roller end When the heat generation amount in the longitudinal direction by the exciting coil 18 is made constant, the temperature of the roller end decreases because the heating roller 10 has a larger surface area at the end that comes into contact with the outside air. . For this reason, generally, in order to maintain the temperature of the roller end portion, the temperature of the central portion is set high. Or it is necessary to adjust heat distribution by the magnetic flux generation means 15.

  In this embodiment, the temperature of the heating roller 10 is adjusted using the temperature detection element 27. Further, by setting the Curie point of the heat generating layer 11 so that the surface temperature of the heating roller 10 is in the vicinity of the fixing temperature, the temperature at the center of the roller is maintained in the vicinity of the fixing temperature. When the heat generating layer 11 reaches the Curie point, the magnetic flux generated by the magnetic flux generation means 15 penetrates and leaks to the outside, causing the magnetic flux capturing coil 51 to generate an induced current. The induced current generated in the magnetic flux trapping coil 51 can inductively heat the end portion of the heating roller 10 that does not exceed the Curie point, thereby assisting heat generation.

  Therefore, it is possible to achieve a uniform temperature distribution over the length and reduce power consumption. The uniform temperature distribution makes it possible to obtain a good fixing state over the entire surface of the recording material, and even in an image where the toner is on the entire surface, the difference in gloss between the center and the edge can be reduced.

(2) With respect to non-sheet passing portion temperature rise As shown in FIG. 3, the width of the recording material P is L _P , the maximum sheet passing width is L _Pmax , the minimum sheet passing width is L _Pmin , and the inner width of the excitation coil 18. Is L _C. In this embodiment, the temperature of the heating roller 10 is adjusted using the temperature detecting element 26. For example, when the recording material P narrower than the inner width L _C of the exciting coil 18 is passed, that is, when L _P <L _C , the non-sheet passing portion outside the recording material P in the longitudinal direction of the heating roller 10. That is, since the recording material P is not deprived of heat by the portion where the recording material P is not passed, the temperature is higher than that of the passing portion. For this reason, the non-sheet passing portion reaches the Curie point earlier than the sheet passing portion. Since the magnetic flux penetrates the part that has reached the Curie point, the temperature rise is reduced. The magnetic flux penetrating the heat generating layer 11 generates an induced current in the magnetic flux capturing coil 51 constituting the magnetic flux capturing means 50, and the generated induced current can inductively heat a portion of the heat generating layer 11 that has not reached the Curie point. it can.

  FIG. 7 shows a modification of this embodiment.

  That is, as shown in FIG. 7, the roles of the excitation coil 18 and the magnetic flux capturing coil 51 can be switched with respect to the heating roller 10.

  That is, according to this modification, the magnetic flux capturing means 50 including the magnetic flux capturing coil 51 and the magnetic core 52 is disposed inside the heating roller 10.

  In this modified example, as shown in FIG. 7, the magnetic core 52 is substantially perpendicular to the center of the cross section of the heating roller 10, that is, upward in the radial direction, and both sides in the horizontal direction, that is, left and right in the radial direction. Extends in the direction.

  Further, the magnetic core 52 and the capture coil 51 are integrally held by a holder 16 having an arc shape disposed in an upper arc shape portion thereof. Therefore, the capture coil 51 is disposed between the holder 16 and the magnetic core 52 in a fixed state.

  Further, a flat lower surface formed by the magnetic core 52 opposite to the upper arcuate portion of the capture coil 51 is carried on the holding stay 22 via the insulating member 19, whereby the magnetic flux capturing means 50. Is installed in the heating roller 10.

  On the other hand, in the magnetic flux generation means 15, the exciting coil 18 is disposed to face the magnetic flux capturing coil 51 and is disposed along the outer peripheral surface of the heating roller 10 at a predetermined distance.

  An insulating support member (not shown) that holds the excitation coil 18 and the magnetic core 17 is disposed outside the excitation coil 18 to maintain a distance from the heating roller 10.

  That is, the exciting coil 18 can be disposed outside the heating roller 10, a high frequency power supply can be connected, and the magnetic flux capturing coil 51 configured in a closed loop can be disposed inside the heating roller 10.

  In the configuration of this modification, the same effect as that of the above-described embodiment can be obtained. Further, the magnetic core 17 or the magnetic core 51 can be omitted as appropriate.

Example 2
A second embodiment of the heating device according to the present invention will be described. In the configuration of the heating device 1 of the first embodiment, a heating roller is used as the fixing rotator 10, but in this embodiment, a fixing film is used as the fixing rotator 10 instead of the heating roller. Other configurations are the same as the configurations of the first embodiment, and members having the same configurations and functions as the members in the heating device 1 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  8 and 9, the fixing film 10 as a heating rotator is a cylindrical electromagnetic induction heating member. The heating layer that generates heat by the action of a magnetic field is a base layer 11, and an elastic layer is provided on the outer periphery thereof. 12 and a release layer 13.

  The film guide member 20 has a substantially semicircular cross section, and the cylindrical fixing film 10 is loosely fitted on the film guide member 20. The pressurizing rigid stay 22 is a horizontally long member disposed above the film guide member 20, and is applied with pressure by a pressurizing spring (pressurizing means) 45 contracted between the pressurizing rigid stay 22 and the frame 44. Is transmitted to the film guide member 20.

  The flange member 23 is fitted on both ends of the film guide member 20 in the longitudinal direction, the position in the longitudinal direction is constant, and the flange member 23 is rotatably attached to the pressurizing rigid stay 22 by a bearing (not shown). . Thereby, the flange member 23 regulates and holds the end portion of the fixing film 10. The flange member 23 holds the end portion of the fixing film 10 and rotates together with the fixing film 10, and also maintains the fixing film 10 in a cylindrical shape to prevent the fixing film 10 from being displaced to the left and right. ing.

  The pressure roller 30 as a pressure member has the same configuration as that of the first embodiment, and both end portions of the core metal 30a rotate via a conductive bearing between chassis side metal plates (not shown) of the heating device. It is arranged to be freely held.

  The pressure roller 30 is rotationally driven by the driving means M in the counterclockwise direction indicated by the arrow in FIG. 8 (see FIG. 8) by the gear 43 attached to the core metal 30a. A rotational force acts on the fixing film 10 by a frictional force between the pressure roller 30 and the outer surface of the fixing film 10 by the rotational driving of the pressure roller 30. As a result, the fixing film 10 slides in the fixing nip portion N with its inner surface in close contact with the lower surface of the film guide member 20. Accordingly, the fixing film 10 is rotated around the outer periphery of the film guide member 20 at a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 30 in the clockwise direction indicated by the arrow.

  In this case, in order to reduce the mutual sliding frictional force between the lower surface of the film guide member 20 and the inner surface of the fixing film 10 in the fixing nip portion N, the lower surface of the film guide 20 and the inner surface of the fixing film 10 in the fixing nip portion N are reduced. A lubricant such as heat resistant grease is interposed between them. Alternatively, the lower surface of the film guide member 20 can be covered with a lubricating member. The film guide member 20 serves to pressurize the fixing nip portion N and support the fixing film 10 and to improve the conveyance stability when the film 10 is rotated.

  The material of the film guide member 20 is preferably a material that has excellent insulation and good heat resistance in order to ensure insulation from the fixing film 10. For example, a phenol resin, a fluorine resin, a polyimide resin, a polyamide resin, a polyamideimide resin, a PEEK resin, a PES resin, a PS resin, a PFA resin, a PTFE resin, an FEP resin, an LCP resin, or the like may be selected.

  The layer structure of the fixing film 10 of this example is the same as that of the heating roller 10 described in Example 1. As described above, the electromagnetic induction heat-generating heat generating layer 11 serving as the base layer and the outer layer are laminated. This is a composite structure of the elastic layer 12 and the release layer 13 laminated on the outer surface thereof. For adhesion between the heat generation layer 11 and the elastic layer 12 or between the elastic layer 12 and the release layer 13, a primer layer may be provided between the respective layers.

  The fixing film 10 of this embodiment having such a layer configuration and having a cylindrical shape has the heat generating layer 11 on the inner surface side and the release layer 13 on the outer surface side.

  As described above, when the alternating magnetic flux acts on the heat generating layer 11, an eddy current is generated in the heat generating layer 11, and the heat generating layer 11 generates heat. The heat is applied to the recording material P as a material to be heated that is passed through the fixing nip N through the elastic layer 12 and the release layer 13 to heat and fix the toner image t.

  Here, the thickness of the heat generating layer 11 is preferably 1 to 100 μm. If the thickness of the heat generating layer 11 is smaller than 1 μm, most of the electromagnetic energy cannot be absorbed, resulting in poor efficiency. On the other hand, if the heat generating layer 11 exceeds 100 μm, the rigidity becomes too high, and the flexibility becomes poor, so that it is not practical to use as a rotating body. Therefore, the thickness of the heat generating layer 11 is preferably 1 to 100 μm.

  It is also possible to provide a heat insulating layer or a sliding layer inside the heat generating layer 11.

  In the configuration of the present embodiment, in addition to the effects of the first embodiment, the use of the fixing film 10 as a heating rotator can reduce the heat capacity as compared with the heating roller 10 of the first embodiment, so that a quick start is possible. .

Example 3
A third embodiment of the heating apparatus according to the present invention will be described. In the configuration of the heating device 1 according to the first embodiment, the exciting coil 18 of the magnetic flux generation unit 15 is disposed inside the heating roller 10 and on the opposite side to the pressure roller 30. Further, the magnetic flux capturing means 50 is arranged outside the heating roller 10 so as to face the exciting coil 18.

  In this embodiment, the exciting coil 18 is disposed on the pressure roller 30 side inside the heating roller 10, and the magnetic flux capturing means 50 is disposed on the inner side of the pressure roller 30. Other configurations are the same as the configurations of the first embodiment, and members having the same configurations and functions as the members in the heating device 1 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In this embodiment, as shown in FIG. 10, when the heat generating layer 11 of the heating roller 10 reaches the Curie point, the magnetic flux penetrates the heating roller 10 as described above and reaches the core 30 a of the pressure roller 30.

  In the present embodiment, a ferromagnetic metal is used for the pressure roller core 30a as in the case of the heating roller 10.

Here, the Curie point of the heating roller core metal 11 T _CT, the Curie point of the pressing roller core metal 30a and T _CK. By setting T _CT > T _CK and setting the pressure roller core metal temperature to be equal to or higher than the Curie point when the heating roller 10 reaches the Curie point, the magnetic flux in the portion of the heating roller 10 that has reached the Curie point is increased. The magnetic flux trapping coil 51 disposed inside the pressure roller 30 is reached. The magnetic flux penetrating from the portion of the heat generating layer 11 of the heating roller 10 that has reached the Curie point generates an induced current in the magnetic flux capturing coil 51, and the generated induced current passes through the Curie point of the heat generating layer 30a of the pressure roller 30. The part not exceeding is induction-heated.

  Therefore, in the configuration of the present embodiment, by providing the magnetic flux capturing means 50 in the pressure roller 10, the same effects as those of the first embodiment can be obtained without increasing the size of the apparatus.

  As a modification of the present embodiment, as shown in FIG. 11, instead of using a heating roller and a pressure roller as the heating rotator 10 and the pressure member 30, respectively, a heating belt 61 and a pressure belt 64 are used. It is also possible to adopt a configuration to be used.

  In this modification, the heating belt 61 is stretched around the tension rollers 62 and 63, and the pressure belt 64 is also stretched around the tension rollers 65 and 66. The configuration of the pressure belt 64 can be the same as that of the heating belt 61.

  That is, each of the heating belt 61 and the pressure belt 64 is an endless belt-shaped electromagnetic induction heating member. The heating layers that generate heat by the action of a magnetic field are the base layers 61a and 64a, and the elastic layers 61b and 64b are separated from the outer periphery thereof. It has a laminated structure having mold layers 61c and 64c.

  Belt guides 71 and 72 are arranged to form a nip portion for holding the recording belt P between the heating belt 61 and the pressure belt 64 and holding the recording material P therebetween. The belt guides 71 and 72 also serve as a holder for the exciting coil 18 and the magnetic core 17 of the magnetic flux generating means 15 and a holder for the magnetic flux capturing coil 51 and the magnetic core 52 of the magnetic flux capturing means 50, respectively. The configuration of the magnetic flux generating means 15 and the magnetic flux capturing means 50 is the same as that of the previous embodiment. Therefore, the re-explanation is omitted.

  According to this embodiment and this modification, the same operational effects can be obtained without providing the heat generating layers 30a and 64a on the pressure roller 30 and the pressure belt 64. That is, in this case, the heat generating layers 11 and 61 a of the heating roller 10 and the heating belt 64 are caused to generate heat by the magnetic flux capturing means 50.

1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus of the present invention. It is a schematic block diagram of one Example of the heating apparatus of this invention. FIG. 3 is a schematic front view of the heating apparatus shown in FIG. 2. It is a schematic structure sectional view showing the layer composition of a heating rotating body. It is a graph which shows the relationship between a heat generating layer depth and electromagnetic wave intensity. It is a figure explaining the magnetic flux capture coil of a magnetic flux capture means. It is a schematic block diagram of the other Example of the heating apparatus of this invention. It is a schematic block diagram of the other Example of the heating apparatus of this invention. It is the front schematic of the heating apparatus shown in FIG. It is a schematic block diagram of the other Example of the heating apparatus of this invention. It is a schematic block diagram of the other Example of the heating apparatus of this invention.

Explanation of symbols

1 Fixing device (heating device)
11 Heat generation layer (electromagnetic induction heat-generating member)
12 Elastic layer 13 Release layer 10 Heating roller, fixing film (heated rotating body)
DESCRIPTION OF SYMBOLS 15 Magnetic flux generation means 16 Guide member 17 (17a, 17b, 17c) Magnetic core 18 Excitation coil 20 Film guide member 22 Holding stay 26, 27 Temperature detection element 30 Pressure roller (Pressure member)
50 Magnetic Flux Capture Means 51 Magnetic Flux Capture Coil 52 Magnetic Core 61 Heating Belt (Heating Rotator)
64 Pressure belt (pressure member)
100 Image forming apparatus N Fixing nip P Recording material

Claims (7)

A heating rotator having an electromagnetic induction exothermic member; magnetic flux generating means for generating heat by putting a magnetic flux in the electromagnetic induction exothermic member; and a pressurizing member in contact with the heating rotator; In a heating device that sandwiches and conveys a material to be heated in a nip formed by contact with the pressure member, and pressurizes and heats,
A heating apparatus, wherein the electromagnetic induction heat generating member is used in the vicinity of a Curie point, and magnetic flux capturing means is provided for capturing the magnetic flux that has passed through the electromagnetic induction heat generating member with the magnetic flux generated by the magnetic flux generation means.   The heating apparatus according to claim 1, wherein the magnetic flux capturing means is a coil forming a closed loop.   The heating apparatus according to claim 1 or 2, wherein the electromagnetic induction heat generating member is heated by an induced current generated by the magnetic flux capturing means.   In the rotational axis direction of the electromagnetic induction exothermic member, the electromagnetic induction exothermic member has a portion exceeding the Curie point and a portion not exceeding the Curie point, and passes through the electromagnetic induction exothermic member from the portion exceeding the Curie point. An induced current is generated in the magnetic flux trapping means when the magnetic flux trapping means captures the generated magnetic flux, and a portion of the electromagnetic induction exothermic member that does not exceed the Curie point is induction-heated by the induced current. Item 4. The heating device according to Item 3.   The heating apparatus according to any one of claims 1 to 4, wherein the magnetic flux capturing means is disposed in the pressure member.   6. The heated material is a recording material on which an unfixed toner image is formed, and the unfixed toner image is heat-fixed on the recording material by passing through the nip portion. The heating device according to any one of the above items. An image forming apparatus comprising: an image forming unit that forms an unfixed toner image on a recording material; and a fixing device that thermally fixes the unfixed toner image on the recording material.
The image forming apparatus according to claim 6, wherein the fixing device is a heating device according to claim 6.

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